This invention relates to a method of disposing of an acidic waste including ferrous or bivalent iron ions. The waste may be, for example, the waste lye of a pickle for articles made of iron and a waste that inevitably results during production of titanium white.
The waste generally includes, besides the ferrous ions, either halogen or sulfate ions and is strongly acidic. The waste should therefore be discharged either to sewerage or a river after disposed of to prevent pollution.
On disposing of the waste, it has been proposed to neutralize the waste, subject the waste to oxidation to form therein precipitate of iron oxides (containing more ferric ions than triiron tetroxide) and/or iron oxyhydroxide (FeOOH), and to remove the precipitate by filtration. The proposal has, however, been tried only on a small scale. This is because the precipitate of the iron compounds is formed in very fine particles and it has been difficult to remove the precipitate from the waste.